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Obstetrics > Fetal Monitoring > Flashcards

Fetal Monitoring Flashcards

1
Q

What are methods of fetal monitoring in labour?

A 
Intermittent auscultation 
Continuous cardiotocography (CTG)
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2
Q

How does intermittent auscultation work? How often?

A

Doppler US for a full minute after a contraction in low risk women

Every 15min in 1st stage
Every 5min throughout second stage

If abnormality - start CTG

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3
Q

How is CTG monitoring carried out?

A 
Abdominal probe (US) or a fetal scalp electrode
Latter is useful if there is doubt about source of heartbeat, poor contact of abdominal probe, obesity and very mobile women but requires rupture of membranes

One transducer records fetal heart rate using US
Other monitors contraction of uterus by measuring tension of abdominal wall - indicates intrauterine pressure

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4
Q

What are indications for electronic fetal monitoring?

A 
Induction of labour
Post-maturity (>42 weeks)
Previous LSCS
Maternal cardiac problems
Pre-eclampsia or hypertension
Prolonged rupture of membranes > 24h
Prematurity < 37 weeks
DM
Antepartum or intrapartum haemorrhage
Small for gestational age
Oligohydramnios
Abnormal umbilical artery Doppler
Multiple preganncy
Meconium stained liquor
Abnormal lie
Oxytocin augmentation
Epidural 
Pyrexia
Abnormality on intermittent auscultation
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5
Q

How do you describe CTG?

A

DR C BraVADO

Define risk
Contractions - per 10 minutes
BRA - Baseline rate
V - variability
Accelerations
Decelerations
Overall impression - normal, non-reassuring, abnormal
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6
Q

How do you define risk? What are indications of high risk?

A

Assess if pregnancy is high or low risk

Maternal medical illness:
Gestational diabetes
Hypertension
Asthma

Obstetric complications:
Multiple gestation
Post-date gestation
Previous C-section
IUGR
PROM
Congenital malformations
Oxytocin induction/augmentation
Pre-eclampsia

Smoking
Drug abuse

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7
Q

How do you work out number of contractions?

A

Each big square is equal to one minute
- count the number of peaks in 10 big squares
If 2 - 2in 10

Assess:
Duration of contraction
Intensity of contraction - assess with palpation

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8
Q

How do you calculate baseline rate

A

Average level of foetal heart rate when any accelerations or decelerations have been excluded
Appears as straight-ish line between other features
Look at CTG and assess what average heart rate has been over last 10 minutes

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9
Q

What is normal fetal heart baseline rate?

A

100-160

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10
Q

What is fetal tachycardia? Causes?

A

> 160bpm

Fetal hypoxia
Chorioamnionitis
Hyperthyroidism
Fetal or maternal anaemia
Fetal tachyarrhythmia
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11
Q

What is fetal bradycardia? Causes?

A

Baseline rate < 100bpm for 3 minutes or more

Postdate gestation
Occipitoposterior or transverse

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12
Q

What is severe prolonged bradycardia? Causes?

A

Less than 80 bpm for more than 3 minutes

Prolonged cord compression
Cord prolpase
Epidural and spinal
Maternal seizures
Rapid fetal descent
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13
Q

What is variability?

A

Variation of the fetal heart rate from one beat to next

Indicator of how healthy fetus is - healthy fetus will consistently be adapting its heart rate in response to changes to environment

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14
Q

What is normal variability?

A

5-25bpm

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15
Q

How do you calculate variability?

A

Look at how much peaks and troughs of heart rate deviate from baseline rate

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16
Q

How is variability categorised?

A

Reassuring: 5-25bpm
Non-reassuring:
< 5 bpm for 30-50min
more than 25 bpm for 15-25 mins

Abnormal:
<5 bpm for > 50 minutes
>25 for more than 25 minutes
Sinusoidal

17
Q

What re causes of reduced variability?

A 
Fetal sleeping (no longer than 40 mins)
Fetal acidosis due to hypoxia
Fetal tachycardia
Drugs - opiates, benzodiazepines, magnesium sulphate
Prematurity < 28 weeks
Congenital heart abnormalities
18
Q

What are accelerations?

A

Upward spike of >15 bpm for >15 seconds
Reassuring feature
Commonly occur when fetus is moving

19
Q

What are decelerations?

A

Downward spike of baseline fetal heart rate >15 bpm for >15 seconds

Reduction in heart rate to reduce myocardial demand

20
Q

What are early decelerations? What causes them?

A

Start when uterine contraction begins and recover when uterine contractions stops

Due to increased fetal intracranial pressure causing increased vagal tone

Physiological
Seen in breech presentation and in second stage of labour

21
Q

What are variable decelerations? When is it concerning?

A

Rapid fall in baseline fetal heart rate with a variable recover phase
Variable in duration
Most often seen during labour and in oligohydramnios

Concerning if:
>60 seconds
Reduced baseline variability within deceleration
Failure to return to baseline
Bisphasic W shape
No shouldering
22
Q

What are causes of variable deceleration?

A

Umbilical cord compression

Umbilical vein is often occluded first causing an acceleration
Then umbilical artery is occluded causing subsequent rapid deceleration
When pressure on the cord is reduced another acceleration occurs then the baseline rate returns
Acceleration before and variable deceleration are known as shoulders
Shoulders indicate fetus is not yet hypoxic and is adapting to reduced blood flow

Variable decelerations without shoulders suggests hypoxia

23
Q

What are late decelerations? Causes?

A

Begin at the peak of uterine contraction and recover after contraction ends

Insufficeint blood flow to the uterus and placenta
Hypoxia and acidosis of fetus

Maternal hypotension
Pre-eclampsia
Uterine hyperstimulation

24
Q

What should be done if late decelerations?

A

Fetal blood sampling for pH

–> Emergency C-section if acidotic

25
Q

What are prolonged deceleration?

A

Lasts for >3 minutes

2-3 minutes = non-reassuring
>3 minutes = abnormal

26
Q

What is sinusoidal pattern? Causes?

A

Smooth regular wave like pattern
Frequency of 2-5 cycles a minute
Stable baseline rate of 120-160bpm
No beat to beat variability

Severe fetal hypoxia
Severe fetal anaemia
FEtal/maternal haemorrhage

27
Q

What is overall impression?

A

Reassuring:
Baseline 110-160
Variability >5 <25
Decelerations: none or early

Non-reassuring/Suspicious
Baseline <100-109 or >161-180
Variability <5 for 30-50m or >25 for 15-25m
Deceleration: Variable for >90mins, for >50% contraction, taking <60s to recover, drop from BR of >60beats, taking >60s to recover, for <30min

Abnormal
Baseline <100 >180
Variability <5 for 50mins+ >25 for 25mins+ Sinusoidal
Decelerations: Late, >50% contraction for >30min, single prolonged for >3mins

28
Q

How can CTG be improved?

A

Left lateral position to shift weight off maternal vessels and correct cord compression
IV fluids if hypotensive
Reduce or stop oxytocin infusion if > 5 in 10 or bradycardia

29
Q

What is fetal blood sampling?

A

Small sample of blood from fetal scalp
Woman is placed in left lateral and a speculum is inserted
Small scratch on fetal scalp and fetal blood collected in capillary tume

30
Q

Results of fetal blood sampling?

A

Normal >7.25 - repeat in 1h if CTG remains abnormal
Borderline 7.21-7.24 - repeat in 30min if CTG remains abnormal
Abnormal <7.20 - immediate C-section

31
Q

CI of fetal blood sampling?

A

Woman has ITP

Woman has blood born viruses

32
Q

What is the normal number of uterine contractions?

A

5 or less in 10 mins

> 5 = tachysystole
Possibly due to over stimulation with IV oxytocin

Obstetrics (53 decks)

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